Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
 #include<bits/stdc++.h>

using namespace std;

int dist[60][60];

void dfs(int x,int y,int g){
   if (dist[x][y]!=0&&dist[x][y]<=g) return;
   if (dist[x][y]==-1) return;
   dist[x][y] = g;
   dfs(x+1,y,g+1);
   dfs(x-1,y,g+1);
   dfs(x,y+1,g+1);
   dfs(x,y-1,g+1);
}

int main(){
    int h,w,cnt=0; cin >> h >> w;
   for (int i = 0; i < 55; i++)
   {
    for (int j = 0; j < 55; j++)
    {
        dist[i][j] = -1;
    }
   } 
   for (int i = 1; i <= h; i++)
   {
    for (int j = 1; j <= w; j++)
    {
        char ch;cin >>ch;
        if (ch=='.')
        {
            dist[i][j] = 0;
            cnt++;
        }
       
    }
   }      
    dist[1][1] = 0;
    dfs(1,1,0);
    if (dist[h][w]==0)
    {
       cout << -1;
    }
    else
    {
        cout << cnt-1-dist[h][w];
    }
  
    return 0;
}